On 18/01/2023 18:27, Kamil Tekiela wrote:
When I read the RFC I was a little sceptical about the deprecation of
string increment functionality. It's something I used in the past and I see
no easy upgrade path. However, after reading this thread and thinking it
over, I realize that deprecation is the right way to go. Someone said that
it's useful when working with Excel. Excel uses bijective base-26 system.
PHP does not. I cannot even explain what logic governs PHP string increment
functionality.
The logic is actually fairly straightforward if you consider breaking
the original string into blocks of alpha, numeric and non-alphameric
characters; so a string like 'C-37AZ99' would be broken into five blocks
of characters ('C', '-', '37', 'AZ' and '99').
Start with the rightmost block, but only if its alpha or numeric: the
process will never increment any block of characters that is non-alphameric.
Increment the current block.
If that increment would result in an overflow (extending the size of
that block) and there is another block to the "left" in the chain of
blocks, then that block is reset to its "base" value (discard the
overflow character), and the same process is repeated for incrementing
the next block in the chain.
The process terminates when there are no more blocks in the chain, or
when the process encounters a non-alphameric block.
The string is then "glued" back together again for the return.
In this regard, when a block is alpha characters, then the increment
behaviour matches "Excel's bijective base-26".
--
Mark Baker
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